This invention relates to the detecting of flaws in substantially cylindrical objects. More particularly, this invention relates to apparatus for rapidly and continuously feeding such objects, for example, container bodies, to an inspection station, and for inspecting them there to detect flaws in portions of their bodies such as their rims.
Apparatus for rapidly feeding a plurality of serially fed substantially cylindrical objects such as container bodies to an inspection station and for inspecting them while they are being rotated there, are well known. Such apparatus are commonly employed in the ferrous can manufacturing industry. However, such apparatus are disadvantageous for several reasons. They usually involve troublesome and complicated machinery, such as large rotating wheels or turrets having multiple peripheral pockets having mandrels for mounting the container bodies thereon, indexing mechanisms for indexing the pockets and mandrels with infeed and discharge systems involving complicated movable intermittent linkage mechanisms such as chucks for transporting the container bodies to and placing them on the mandrels. Such mechanisms are expensive and require frequent repair. Also, such apparatus are often not fully effective for detecting flaws in certain portions, such as the rims, of container or can bodies. One such apparatus inspects lap seamed beer and beverage can bodies for cracks and leaks. The can bodies usually have a flanged open end and an end closed by an integral bottom or by an end closure. The flanged can body is placed on a mandrel in a pocket, its open end is sealed and it is internally pressurized. This apparatus and procedure is often ineffective for detecting cracks in rim and flange areas because the seal used for sealing the open end abuts, covers, and prevents effective inspection of the rim and flange areas. This pressured inspection system is only useful in relation to can bodies closed at one end by an integral or separate end closure secured thereto. Rejection and disposal of a defective can body due to say a flange crack is wasteful because it involves disposal of the integral end or end closure material, even though the end may not be defective. It also would be desirable if currently available container body testing apparatus would operate more rapidly. Another disadvantage of currently available container body inspection apparatus is that containers get damaged and there is much down time due to jams caused by irregularly-shaped, out-of-round, or otherwise damage or flawed containers. For example, a conically-shaped container having different end diameters may not be physically acceptable to or registerable in and may therefore jam in current inspection stations. This might also result in damage to an additional number of containers for failure of the apparatus to immediately shut off.
Currently available inspection apparatus tailored to inspect container body rims for flaws such as cracks, have been less than fully effective for inspecting rims of containers such as cans whose bodies and rims are slightly out-of-round, and have been totally ineffective when the bodies and rims are greatly out-of-round. The reason for this is that such sensors are only effective within a certain sensor-to-rim gap distance or sensitivity range. The prior art has been only partly successful in effectively sensing gap variations but only narrow gap variations within the sensor's overall gap sensitivity range. This partial success has been achieved by use of complicated electronic gap variation compensation circuits. Prior art detection systems are totally ineffective with respect to wide gap variations such as produced by grossly out-of-round container bodies whose rims have portions which go greatly beyond either the very narrow or the overall sensor gap sensitivity range. It would therefore be desirable to provide a detection apparatus and systems which, regardless of whether rims are slightly or grossly out-of-round, would provide only minimum gap variations within acceptable limits that are within the sensor's overall gap sensitivity range.
Objectives of the inspection apparatus of this invention are to overcome the above and other disadvantages by providing a simply designed, relatively small, trouble-free, inexpensive-to-build and operate inspection apparatus which operates continuously without use of complicated intermittent linkage mechanisms. The apparatus does not employ pressurizing and sealing means and is highly effective for inspecting rims and flanges of container bodies, especially for small imperfections such as cracks, and peaked flanges. The apparatus operates rapidly with objects spending much less total time in the inspection station. A highly significant advantage of the inspection apparatus of this invention is its capability of operating trouble-free for long periods of time, without jams and with minimal damage to containers or wastage of container materials. The apparatus effectively senses and is seldom jammed by out-of-round, irregularly shaped, damaged, or flawed containers. When a container is too mangled or otherwise cannot be passed through the apparatus, it shuts off automatically on a single container jam without damage to any subsequent containers.
Another highly significant advantage of the inspection apparatus is that it operates while maintaining a nearly uniform distance between a rotating container body, say its rim and flange edges, and a fixed adjacent detecting means. The apparatus of this invention provides a mechanical system of rotating slightly a grossly elliptical or out-of-round can bodies such that their rims only cause minimum gap variations which are within acceptable limits that are within the sensor's overall gap sensitivity range. The apparatus is therefore capable of employing currently available sensors for inspecting and detecting flaws in cylindrical bodies regardless of whether they are slightly or grossly elliptical, or are egg shaped or are otherwise out-of-round. Sensors employed with the apparatus of this invention can be employed with a very short sensor-to-rim gap distance which allows the sensor to be highly sensitive to very small variations, for example due to slightly peaked flanges and even very tiny flange cracks and dents. The sensors are therefore capable of inspecting a container body for, and simultaneously detecting large variety of flaws which would render the two or three piece container bodies unacceptable aesthetically, or for further processing or certain end uses, such as due to their unacceptable shape, peaked flanges, body blank chips in the lap seam cement or solder, or excess cement or solder at or openings in the laps at the flange lap cross overs of lap side seamed bodies.
Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses preferred embodiments thereof.